The issue I'm having is on my Dell XPS 15 9570 after updating to Windows 10 1903.
After updating, any time the laptop is on battery power, the display dims whenever a dark scene like a video editor or game is on screen, and gets brighter whenever a light scene like a web browser is on screen. This has been an issue for a long time, but toggling Display Power Saving on and off in the Intel UHD Graphics Control Panel used to fix the issue. However, since updating to 1903 and installing the latest Intel graphics driver, the toggles in the control panel to turn display power saving on and off no longer do anything. So now, basically any non-white content on screen makes the display dim to a point where text is nearly unreadable.
This issue is very frustrating and I have had to roll back to 1809 because of it. Just wanted to make sure this issue was known and I hope to see a fix for this soon.